Method of detecting amount of remaining sheets of paper

摘要

A method of detecting the amount of sheets of paper remaining in a paper feeding cassette of a printing apparatus by calculating a difference in the number of operations of a lifting means (300) for lifting a knock-up plate (201) toward a pickup roller (120) when the maximum number of sheets of paper is loaded in the cassette and when only one sheet of paper is left in the cassette and calculating the amount of consumed paper per one operation of the lifting means as a set value; lifting the knock-up plate (201) when the cassette enters in the printing apparatus until the loaded paper closely contacts the pickup roller and counting the number of operations of the lifting means then; and calculating the amount of paper remaining in the cassette considering the number of operations counted and the set value. Thus, the amount of sheets of paper remaining in the cassette can be easily determined without opening the cassette so that a printing job can be prevented from being stopped due to lack of paper.